TDCOSMO: IX. Systematic comparison between lens modelling software programs: Time-delay prediction for WGD 2038−4008
TDCOSMO: IX. Systematic comparison between lens modelling software programs: Time-delay prediction for WGD 2038−4008
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TDCOSMO：九。
DOI：
10.1051/0004-6361/202243401
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发表时间：
2022
影响因子：
6.5
通讯作者：
Palmese, A.
中科院分区：
文献类型：
--
作者：
Shajib, A. J.;Wong, K. C.;Birrer, S.;Suyu, S. H.;Treu, T.;Buckley-Geer, E. J.;Lin, H.;Rusu, C. E.;Poh, J.;Palmese, A.
测量哈勃常数的替代方法的重要性，如时间延迟宇宙学，突出了最近的哈勃紧张局势。在我们接受新物理学作为这种紧张的根源之前，彻底调查并排除所有测量方法中的系统性偏差是至关重要的。在这项研究中，我们通过比较两个团队使用两种不同的软件程序：GLEE和LENSTRONOMY对系统WGD 2038−4008的独立和盲时间延迟预测，来检查时间延迟宇宙学的透镜建模过程中的系统偏差。两个团队预测的时间延迟结合了偏转器的恒星运动学和视线结构的外部会聚。两个团队的非盲时间延迟预测在1.2σ内一致，这意味着一旦测量了时间延迟，推断的哈勃常数也将相互一致。然而，幂律模型的斜率和外部剪切之间存在着104 σ的差异，这在引入恒星运动学和外部会聚之前的透镜模型水平上是一个显著的差异。我们确定重建的点扩散函数（PSF）的差异是这种差异的来源。当两个团队使用相同的重建PSF时，我们取得了很好的一致性，在± 0.6σ内，这表明来源重建算法和研究者选择的潜在系统学得到了很好的控制。我们建议未来的研究根据需要对PSF进行超采样，并对PSF重建的多个算法或实现进行边缘化，以减轻与PSF相关的系统性。未来的研究将测量系统WGD 2038−4008的时间延迟，并根据我们的质量模型推断哈勃常数。
The importance of alternative methods for measuring the Hubble constant, such as time-delay cosmography, is highlighted by the recent Hubble tension. It is paramount to thoroughly investigate and rule out systematic biases in all measurement methods before we can accept new physics as the source of this tension. In this study, we perform a check for systematic biases in the lens modelling procedure of time-delay cosmography by comparing independent and blind time-delay predictions of the system WGD 2038−4008 from two teams using two different software programs: GLEE and LENSTRONOMY. The predicted time delays from the two teams incorporate the stellar kinematics of the deflector and the external convergence from line-of-sight structures. The un-blinded time-delay predictions from the two teams agree within 1.2σ, implying that once the time delay is measured the inferred Hubble constant will also be mutually consistent. However, there is a ∼4σdiscrepancy between the power-law model slope and external shear, which is a significant discrepancy at the level of lens models before the stellar kinematics and the external convergence are incorporated. We identify the difference in the reconstructed point spread function (PSF) to be the source of this discrepancy. When the same reconstructed PSF was used by both teams, we achieved excellent agreement, within ∼0.6σ, indicating that potential systematics stemming from source reconstruction algorithms and investigator choices are well under control. We recommend that future studies supersample the PSF as needed and marginalize over multiple algorithms or realizations for the PSF reconstruction to mitigate the systematics associated with the PSF. A future study will measure the time delays of the system WGD 2038−4008 and infer the Hubble constant based on our mass models.